1. Field of the Invention
The invention relates to a fitting for connecting in a sealing manner to an end of a pipe comprising a plastic material, having a base body and having a support body, wherein the base body consists of a metal. The invention also relates to a system having such a fitting, having a composite or multilayer pipe and having a sleeve, and to a system having such a fitting, having a plastic pipe and having a sleeve. The invention, furthermore, also relates to the use of such a fitting for connecting to a composite or multilayer pipe and to the use of such a fitting for connecting to a plastic pipe.
2. Description of Related Art
A fitting for connecting to a pipe in a sealing manner is known from the prior art of EP 0 728 979 A1. The fitting (or the connecting piece) completely consists of a metal and has a support body (or a cylindrical section), onto which the pipe is fitted. A press ring is connected externally to the fitting and the pipe, which press ring is pressed with a pressing tool to secure the connection to the fitting and the pipe.
This pipe connection has the disadvantage that leakages can occur with the connection to a composite or multilayer pipe. Leaks can thus develop between the support body consisting of metal and the composite or multilayer pipe owing to different degrees of expansion when there are changes in temperature, which make the entire pipe connection leaky. In order to prevent this, an additional sealing element can be used, for example an O-ring. However, this leads to higher production costs and to difficulties when inserting the pipe to be connected into the pipe connection.
Since composite or multilayer pipes are, for example, often used in sanitary engineering, particularly for piping systems for underfloor heating and concealed pipe systems, it is desirable for the connections with these pipes to have a high reliability and a long durability. In order to deal with the problems of conventional connections to composite or multilayer pipes, various approaches are followed in the prior art. Thus, fittings are known where the support bodies 15 of these fittings have been overmolded with plastic. This has the disadvantage that the production of such fittings, owing to the additional overmolding process, is often elaborate and expensive. Furthermore, the connection between the metal of the fitting and the overmolded plastic layer often does not retain its reliability.
Another alternative from the prior art is the use of fittings manufactured completely from plastic. However, these fittings, compared to fittings manufactured from metal, have the disadvantage that they have a sharp-edged inner profile. Thus, it is advantageous, for example with T-piece fittings made of metal, for the inner profile of the fitting to be designed rounded with a certain radius at the tee edge, in order to reduce the pressure loss of the conveyed medium. With fittings manufactured completely from plastic this is not possible or is only possible with elaborate and cost-intensive post-processing.